1. Field of the Invention
The present invention relates to a printing apparatus capable of printing operation utilizing a font cartridge incorporating a font ROM in which a predetermined type font is stored.
2. Related Background Art
Recent remarkable progress in electronic technology has realized commercialization of various electronic appliances such as personal computers and word processors not only to the office market but also to the personal market. For the output from such electronic appliances there are employed printers of various output forms such as wire dot printers, thermal printers, ink jet printers etc.
In such printers, changeable in type fonts have been achieved by employing a detachable font cartridge incorporating a font ROM in which a type font is stored and printing a dot pattern of a desired type style developed into a dot image on a recording sheet, or by printing, on a recording sheet, a dot pattern of a desired typestyle developed into a dot image for example of italic style stored in a specified area of a font ROM incorporated in the printer, in response to the instruction from a host apparatus in either case.
In the above-explained printer utilizing a detachable font cartridge, if said font cartridge is detached from the printer while the power supply is turned on, an erroneous operation may result from the errors in the data on the bus line, since the font data to be printed is stored for example in a memory.
For this reason it has been customary to prevent such erroneous operation by resetting the data processing in the printer when detaching the font cartridge from the printer, or by prohibiting the detaching of the font cartridge while the power supply is turned on.
In printers where the data processing is reset at the detaching of the font cartridge, data and control commands entered before said detachment are inevitably lost, so that it is impossible to effect a continuous printing operation with different type fonts or different font cartridges. It is therefore impossible to continuously print different type styles on a same sheet.
On the other hand, in order to resolve the above-explained drawback with an incorporated font system, it is necessary to increase the number of printable type fonts, leading to a significant increase in the cost of the apparatus.